Internal combustion engine



April 18, 1939. M. MALLORY INTERNAL GOMBQSTION ENGINE Filed April 19, 1937 Snow,

Patented Apr. 18, 1939 PATENT OFFICE INTERNAL COIWBUSTION ENGINE Marion Mallory, Detroit, Mich.

Application April 19, 1937, Scrial No. 137,843

8 Claims.

This invention relates to new and useful improvements in an internal combustion engine in which each power unit, corresponding to a cylinder in a conventional type of engine, comprises two cylinders which are in constant communication with each other'through a common combustion chamber. The pistons operating in the cylinders are connected to a common crank shaft but are so arranged that one piston leads the other.

The fundamental object of my invention is to provide means for controlling the burning of mixture in the combustion chamber of an extremely high compression internal combustion engine, whereby the burning of the mixture is so controlled that it burns more slowly. This reduces the violent pressure rise of the unburned mixture, thereby eliminating self-ignition or detonation and, at the same time, dissipating the explosion energy over a longer period in degrees of crank shaft rotation, which in turn gives more power.

The construction and operation of the invention will be fully explained in connection with the accompanying drawing, in which,--

Fig. 1 is a vertical transverse section through one of the power units of an engine constructed according to the principles of the'invention.

Fig. 2 is a diagrammatic view illustrating the successive relative positions of the pistons during the downward stroke.

Fig. 3 is a sectional view of a power unit looking upward toward the combustion chamber.

Fig. 4 is a sectional view of the combustion chamber .looking downwardly, illustrating diagrammatically the effect of the explosion following ignition.

Fig. 5 is a similar view illustrating the effect of the explosion in the combustion chamber of a conventional engine, when the spark plug is 10- cated at the side of the combustion chamber.

Fig. 6 is a similar view illustrating the eiiect of the explosion in the combustion chamber of a conventional engine, when the spark plug is located at the center of the combustion chamber. As shown in the drawing, the engine to which the invention pertains comprises a crank case I0, within which a crank shaft Il-ls'mounted. Each power unit or cylinder unit comprises a main cylinder l2, having a combustion chamber H at its upper end, and a smaller cylinder [3, with an extension M of the combustion chamber connecting the upper ends of the cylinders, and

pistons l5 and I6 reciprocable in the respective cylinders. Of course, the engine may have as manyof these power or cylinder units as desired, corresponding to the number of cylinders in a conventional engine. I

The piston 15, here shown as the larger piston, has a connecting rod l1 provided with a bearing member I8 on the crank pin I 9 of the shaft II.

This bearing member has a cap 20 secured by bolts or the like. The smaller piston l6 has a connecting rod 2| connected to a pin 22 mounted in an-extension 23 of the member l8.

The top of the combustion chamber I 2 has an inlet port 24 controlled by a valve '25. This valve is normally held closed by'a spring 26, but is adapted to be opened mechanically by a cam 21 on theshaft 28, which rotates at one half the speed of the crank shaft ina four cycle engine. The cylinder also hasthe usual exhaust valve 29, which is operated in a similar manner.

In connection with the intake port 24, I have shown the usual means for supplying fuel mixture, comprising an air intake 30, a venturi 3|, a carburetor having a nozzle 33 discharging into the venturi, and a throttle valve 34 on the engine side of the fuel nozzle.

A spark plug 35 is located on the side of the.

combustion chamber directly opposite to the small cylinder l3. If it is desired to use socalled solid injection in connection with spark ignition, the injector will be located, as shown at 36, at the side of the cylinder l2 diametrically opposite to the spark plug 35 and adjacent the cylinder [3.

In order to demonstrate clearly the manner in which my invention operates to eliminate detonation and at the same time to increase the efliciency of the engine, I will first review briefly the causes and effects of detonation. In the conventional combustion chamber shown at 31 in Fig. 6, in which the spark occurs atthe center of the combustion chamber, the burning gases expand and advancewith the explosion on a substantially circular flame front 38 so rapidly, as compared to the increase in volume resulting from the movement of the piston, that the pressure is built up to a point where self-ignition occurs. This causes a second, more violent and instantaneous explosion throughout the remainder of the combustion chamber, which is called detonation. It not only causes knocks and undue stress on the mechanical parts of the engine, but also causes a loss in power because the burning is so instantaneous that it is completed before the crank is far enough advanced beyond dead center to, give sufiicient leverage on the crank for the best results from the kinetic energy of the explosive .force,

In the combustion chamber 39 of a conventional engine shown in Fig. 5, ihwhich the spark occurs at the side of the combustion chamber and the flame from the explosion advances on the circular front 40, the detonation is even worse because there is a large area of unburned mixture subjected to pressure than in the combustion chamber of a conventional engine such as is shown at 31 in Fig.6.

In the present finvention, I eliminate detonation by relieving the excessive pressure of the unburned mixture which would normally be built up in the combustion chamber of a conventional engine in front of the burning gases which succeed the spark. It will be noted that the piston I6 leads the piston I at the top of the stroke by about as measured by the rotation of the the "travel of the crankshaft, and the spark the cylinder I3.

occurs at this time, practically all of the the fuel mixture will'then be in the combustion chamber I2 and the piston I6 will be moving downwardly as the flame front radiates from the spark gap, while the piston I5 is stillmoving toward dead center position. The spark gap. islocated at the side of the combustion chamber I2 remote from As shown inFig. 4, the flame front advances on the line but the downwardly moving piston in the cylinder I3 allows some of the unburned mixture to 'flow into the latter, relieving the pressure which might otherwise behigh enough to cause self-ignition, with its resultant detonating eifect. It is therefore important that the two cylinders have free communication with each other through the common combustion chamber and that the spark plug be located in the combustion chamber I2 at a point remote from the cylinder l3.

In addition to eliminating detonation, the timing of the two pistons, with one leading the other, the location of the crank pins and their direction of movement with reference to the cylinder axes at the time of the explosive impulse increases the" eflciency of the engine. The increase in volume of the combustion chamber, as the crank pin I9 starts downwardly, is more rapid than in the conventional engine, since the small piston is thenwell on its downward stroke. This means that the increase in pressure due to the burning of the mixture will not be as rapid andthis in turn causes slower burning. The highest pres-- of engine.

On the other hand, the burning is too violent in the conventional engine at the start of the downward stroke, because the burning itself raises the pressure, of the remaining unburned mixture and thereby accelerates the burning so that the kinetic energy of the explosion is.exhausted before the crank is far enough-on its downward stroke to exert the greatest leverage. Then as the piston movement is accelerated in comparison with the angular movement of the crank, the increase in the volume oi the combustion chamber is likewise accelerated, resulting in lower pressure, a slowing up of the burning, and the ing the top of its stroke, or'while there .is a deflnite flow from the cylinder I3 to the combustion chamber I2. In other words, the liquid fuel is injected into a medium that is highly turbulent,

not stagnant. Later in the cycle, there will be a flow from the combustion chamber I2 back into the cylinder I3. Thus the engine provides ideal turbulence which is very desirable for the injector type of spark ignited engines.

In the present embodiment of the invention,

both the intake valve and the exhaust valve are in the large combustion chamber I2, and in timing them, the small piston is not to be considered. In .other words, the valves are timed as they would be in a conventional engine having only the one piston I5. After the exhaust stroke, the exhaust valve should close when the large piston I5 is 4 to 6 past dead center position and the intake valve should open when the, large piston I5 is about 2 past dead center position.

Due to the fact that the small piston I6 reaches top dead center position approximately 10 ahead of the" piston I5, it will have completed 12 or more of its downward stroke, as measured by the rotation of the crankshaft, be-

fore the intake valve opens. This means that no mixture will be drawn into the small cylinder during the early part of the intake stroke,but inasmuch as there is at this time an exhaust pressure in the combustion chamber I2, some of the exhaust gases therefrom will be forced on drawn back into the small cylinder, and by the time that the intake yalve is opened suil'iciently to admit a charge, the larsejpiston will bemoving rapidly downwardly and-will create a suction which opposes the suction created by the -:?mall piston. Furthermore, the speed of travel of the small piston is rapidly decelerated on the latter part of the downwardstroke, while the travel of the large piston is still being accelerated.

The result of this relative travel of the two pistons is that there will not be a very rich mixture nor a very dense charge in the small cylinder. This is a very desirable condition because the ignition will always take place in the richer mixtureand the burning will finish in a weak mixture, which causes a smoother wave of burning and eliminates detonation.

It is well known that low grade fuels detonatebadly, although they are more difficult to ignite.

If higher compression is used to make ignition less diiilcult, the detonation is worse. With my engine, however, high compression can be used without detonation, because the leading piston moving downwardly, as the flame front advances, relieves the pressure of the unburned mixture.

The invention may also be used in connection with a Diesel or self-ignited engine with similar advantages. gins at the point of injection, the injector should be located where the spark plug is located in an electrically ignited engine; that is, at a point remote from the leading piston. The latter will then make room for expansion in front of the flame and prevent detonation inthe manner above explained with reference to electrical ignition. Y

However, since the self-ignition bea While I have referred to a four cycle engine in explaining the "construction and operation of the invention, it will be understood that this is for the purpose of illustration only. The invention relates primarily to the combustion chamber and the control of pressures therein. It will be apparent that the constructional details of the engine which do not affect such control may be modified without departing from the scope of the invention as claimed.

Having thus described the invention, what I claim as new and desire to secure by Letters Patent is:

1. An internal combustion engine comprising two cylinders with a common combustion chamber connecting their upper ends, pistons reclprocable in the respective cylinders with one piston leading the-other,- so that there is a flow through the combustion chamber from the cylinder containing the leading piston into the other cylinder during the latter part of the compression stroke, a fuel injector directly in the path of said flow, and a spark plug located at the top of the cylinder containing the lagging piston and at a point remote from the communication between the two cylinders, whereby the leading piston provides an expanding chamber in front of the flame as the latter advances from the point of ignition.

A four cycle internal combustion engine comprising a cylinder, a piston reciprocable therein, a combustion chamber above the piston and having an intake port and an exhaust port in the top thereof, means for charging the cylinder with a combustible mixture through said intake port and igniting the same at one side of the combustion chamber before said piston reaches top dead center position on its compression stroke, and mechanical means for immediately thereafter expanding the volume of said chamber at a point in advance of the flame propagation from the point of ignition, whereby to prevent such a rise in pressure as to cause self-ignition of the remaining unburned mixture 3. A four cycle internal combustion engine comprising a cylinder, a piston reciprocable therein, a combustion chamber above the piston and having an intake port and an exhaust port in the top thereof, means for charging the cylinder with combustible mixture through said intake port, means for electrically igniting said mixture at one side of the combustion chamber before said piston reaches top dead center position on its compression stroke, and mechanical means for then immediately expanding the volume of said chamber at a point in advance of the flame propagation from the point of ignition.

4. An internal combustion engine comprising a main power cylinder and an auxiliary cylinder with a common combustion chamber connecting their upper ends, pistons reciprocable in the respective cylinders with the piston in the auxiliary cylinder leading the other piston, both of said cylinders having a common fuel mixture inlet port and a common exhaust port in the combustion chamber directly above the lagging piston, means for charging the main cylinder with combustible mixture through said intake port, means for electrically igniting said mixture at the side of the main cylinder remote from the auxiliary cylinder approximately at the time that the piston in the auxiliary cylinder starts downwardly on the power stroke, thereby partially relieving the pressure of the unburned mixture in advance of the flame front.

5. An internal combustion engine comprising a main power. cylinder and an auxiliary cylinder, a combustion chamber covering the end of the main cylinder and extending over a small portion only of the auxiliary cylinder, an intake port and an exhaust port in the top of the combustion chamber, said cylinders having no other inlet or outlet, pistons operable in the respective cylinders with the auxiliary piston leading the main power piston, and a spark plug located atthe side of the combustion chamber remote from the auxiliary cylinder, the spark being timed to occur when the auxiliary piston is substantially at the extreme top of its cylinder, whereby there is' an immediate expansion from the combustion chamber in the direction of the auxiliary piston to partially relieve the pressure developed in advance of the flame front and thereby prevent detonation.

6. An internal combustion engine comprising two cylinders, pistons reciprocable in the respective cylinders with one piston leading the other, a combustion chamber above the lagging piston and in constant communication with the upper end of the cylinder containing the leading piston, both of said cylinders having a common fuel mixture intake port and a common exhaust port in the combustion chamber above the lagging piston, and means for supplying fuel mixture through said intake port to the combustion chamher and igniting the same, there being at the time of ignition substantially no space over the leading piston, whereby all of the mixture is forced into the combustion chamber over the lagging piston preceding ignition.

'7. An internal combustion engine comprising two cylinders, pistons reciprocable in the respective cylinders with one piston leading the other, a combustion chamber above the lagging piston and in constant communication with the upper end of the cylinder containing the leading piston, both of said cylinders having a common fuel mixture intake port and a common exhaust port in the combustion chamber above the lagging piston, and means for supplying fuel mixture through said intake port to the combustion chamber and igniting the same at the time when the leading piston is substantially at the top of its stroke, there being at that time substantially no space over the leading piston.

8. An internal combustion engine comprising two cylinders, pistons reciprocable in the respective cylinders with one piston leading the other, a combustion chamber over the lagging piston and in constant communication with the upper end of the cylinder containing the leading piston, there being substantially no space over the leading piston when it is at the top of its stroke. both of said cylinders having a common fuel mixture inlet port and acommon exhaust port in the combustion c mber above the lagging pis ton, means for supplying fuel mixture through said intake port to the combustion chamber, and means for igniting said mixture at a point remote from the leading piston as the latter starts downwardly on its power stroke, thereby partially relieving the pressure of the unburned mixture in advance of the flame front.

MARION MAILORY. 

